android 5.0新特性 RecyclerView使用初级

     RecyclerView是google 用来取代ListView和GridView等控件。其很好地抽象出了ViewHolder等类。本文给出一个RecyclerView的demo：

1.若是android studio 需要配置gradle

  配置如下：

dependencies {
...
compile 'com.android.support:recyclerview-v7:22.2.1'
}

2. activity_main.xml（很简单只有一个RecyclerView）

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/main_container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity">

<android.support.v7.widget.RecyclerView
android:id="@+id/my_recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbars="vertical" />

</LinearLayout>

3. MainActivity.java文件

public class MainActivity extends ActionBarActivity {

private RecyclerView mRecyclerView;
private RecyclerView.Adapter mAdapter;
private RecyclerView.LayoutManager mLayoutManager;
private List<String> mData;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
// setlayoutManager
mLayoutManager = new LinearLayoutManager(this);
mRecyclerView.setLayoutManager(mLayoutManager);
//setAdapter
mData = new ArrayList<>();
for (int i = 0; i < 40; i++) {
mData.add("this is position:" + i);
}
mAdapter = new MyRecycleViewAdapter(mData, this);
mRecyclerView.setAdapter(mAdapter);
}

}

        在该类中，我们设置了RecyclerView的Adapter。 另外注意，RecyclerView并没有指定元素的显示方式（如水平、gridView、瀑布流方式）。本文仅给出简单的显示方式，设置其RecyclerView的LayoutManager()为LinearLayoutManager。

4.item.main.xml布局为左边textView 右边一个image

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/item"
android:layout_width="match_parent"
android:layout_height="?listPreferredItemHeight"
android:clickable="true"
android:focusable="true"
android:foreground="?selectableItemBackground">

<TextView
android:id="@+id/text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_marginLeft="@dimen/activity_horizontal_margin"
android:textAppearance="?android:attr/textAppearanceMedium" />

<ImageView
android:id="@+id/handle"
android:layout_width="?listPreferredItemHeight"
android:layout_height="match_parent"
android:layout_gravity="center_vertical|right"
android:scaleType="center"
android:src="@drawable/ic_reorder_grey_500_24dp" />
</FrameLayout>

5.  现在我们来定义MyRecyclerViewAdapter如下（需要继承一个携带<ViewHolder（泛型）>的RecyclerView.Adapter类）

public class MyRecycleViewAdapter extends RecyclerView.Adapter<MyRecycleViewAdapter.MyViewHolder> {
private List<String>mData;
private Context mContext;

public MyRecycleViewAdapter(List<String> mData,Context context) {
this.mData = mData;
mContext=context;
}

@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView= LayoutInflater.from(mContext).inflate(R.layout.item_main,parent,false);
return new MyViewHolder(itemView);
}

@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
holder.text.setText(mData.get(position));
holder.itemView.setTag(mData.get(position));
}

@Override
public int getItemCount() {
return mData.size();
}

public static class MyViewHolder extends RecyclerView.ViewHolder{
public ImageView image;
public TextView text;
public MyViewHolder(View itemView) {
super(itemView);
image= (ImageView) itemView.findViewById(R.id.handle);
text= (TextView) itemView.findViewById(R.id.text);
}
}
}

以上代码，其实经常使用listView的同学一定不陌生。需要ViewHolder，以及将数据填充。

public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType)

方法需要我们返回一个自己创建的ViewHolder

public void onBindViewHolder(RecyclerView.ViewHolder holder, int position)

该方法需要我们将数据和ViewHolder绑定。